It is proposed that an extensive physiological, metabolic and evolutionary study be made of species of Acinetobacter, a ubiquitous bacterium normally found in soil, water and also indigenously in man (Herellea, Mina). The genetic transformation system and a recently discovered generalized transducing phage for this organism will be used to obtain evidence for possible gene transposition during evolutionary divergence of various species. There is little or no restriction of DNA among different strains of this bacterium thus making possible a wide range of interspecies genetic experiments. A beginning will be made in the genetic mapping of the acinetobacters. Explanations will be sought for the origin of the wide range of DNA compositions (37-47) mole percent (G plus C) found in genetically related species in terms of gradual change in gene structure, the rare introduction of DNA from unrelated species, as well as the occurrence of extrachromosomal elements (plasmids). Particular emphasis will be given to studies of order and regulation of the genes for the tryptophan biosynthetic pathway, the glucose dissimilatory pathway, and the cyclic pathway for conversion of 2,3-butanediol to acetate. Since acinetobacters have been shown to be responsible for serious infections (meningitis, bacterial endocarditis, pneumonia, septicemia, respiratory tract and urinary infections) in the very young, the aged, as well as in individuals recovering from surgery, or on a regime involving long term use of antibiotics or immunosuppressive drugs, we propose to develop a simple and rapid diagnostic procedure for clinical or taxonomic use in the unequivocal identification of acinetobacters. The possible relationship of the oxidase-positive moraxellas and the oxidase-negative acinetobacters will be explored.